The LCD (Liquid Crystal Display) possesses advantages of thin body, power saving and no radiation to be widely used in many application scope, such as LCD TV, mobile phone, personal digital assistant (PDA), digital camera, notebook, laptop, and dominates the flat panel display field.
Most of the liquid crystal displays on the present market are back light type liquid crystal displays, which comprise a shell, a liquid crystal display panel located in the shell and a backlight module located in the shell. The liquid crystal display panel is a major component of the liquid crystal display. However, the liquid crystal display panel itself does not emit light and needs the back light module to provide light source for normally showing images.
Generally, the liquid crystal display panel is formed by laminating two glass substrates and the liquid crystals are injected between the two glass substrates. At the relative inner sides of the two glass substrates, the pixel electrode and the common electrode are respectively located, and the light of backlight module is reflected to generate images by applying driving voltages to control whether the liquid crystal molecules to be changed directions.
In present LCDs, the color washout phenomenon under wide view angle happens and the situation particularly becomes more obvious in the Vertical Alignment (VA) type LCDs. As shown in FIG. 1, for improving the color washout under wide view angle of the VA type liquid crystal display, the Charge Sharing pixel design is utilized in prior art, i.e. the pixel is divided into two areas of a Main Pixel 100 and a Sub Pixel 200, and the Main Pixel 100 comprises a first thin film transistor T1, a first storage capacitor CST1 and a first liquid crystal capacitor CLC1, and the Sub pixel 200 comprises a second thin film transistor T2, a second storage capacitor CST2 and a second liquid crystal capacitor CLC2, a charge sharing thin film transistor T3 and a charge sharing capacitor CST3. Both the gates of the first thin film transistor T1 and the second thin film transistor T2 are electrically coupled to the charging scan line Gate1(m), and sources are both electrically coupled to the data line Date(n), and m and n are both positive integers, and Gate1(m) represents an mth charging scan line Gate 1, and Date(n) represents an nth data line Date; one ends of the first storage capacitor CST1, the second storage capacitor CST2, and the charge sharing capacitor CST3 are electrically coupled to the drain of the first thin film transistor T1, the drain of the second thin film transistor T2 and the drain of the charge sharing capacitor CST3, respectively, and the other ends are all electrically coupled to common voltage signal line Com(m); the gate of the charge sharing thin film transistor T3 is electrically coupled to the charge sharing scan line Gate2(m), and the drain is electrically coupled to the charge sharing capacitor CST3. As normal display, the charging scan line Gate1(m) is activated, and meanwhile, the charge sharing scan line Gate2(m) is deactivated, and the Main Pixel 100 and the Sub Pixel 200 are at the same voltage level; then, the charging scan line Gate1(m) is deactivated, and meanwhile, the charge sharing scan line Gate2(m) is activated, with the function of the charge sharing capacitor CST3, the voltage level of the Sub Pixel 200 is lower than the voltage level of the Main Pixel 100. Different voltage levels make twisted distributions of the liquid crystal molecules in two display areas different. Accordingly, the effect of improving the color washout under wide view angle is obtained. As shown in FIG. 2, FIG. 3, the charge sharing capacitor CST3 in the pixel utilizing the charge sharing technology of prior art is constructed by an Indium Tin Oxide (ITO) layer upper electrode plate 420, a metal lower electrode plate 20 and an insulative layer 30 sandwiched between the two plates, wherein the ITO layer upper electrode plate 420 and the pixel electrode layer 410 are in the same layer, and the ITO layer upper electrode plate 420 is coupled to a drain of the charge sharing thin film transistor T3 with a via 305, and the metal lower electrode plate 20 is employed as a pixel common electrode coupled to a common voltage signal line Com(m).
However, in practical production, the ITO residue issue may occur, and the short occurs to the ITO layer upper electrode plate 420 of the charge sharing capacitor CST3 and the ITO pixel electrode 410 which results in the malfunction of the charge sharing. The short problem under the same gray scale level makes the sub pixel is brighter than sub pixels of the other pixels, and the micro spot appears on the liquid crystal display panel. At present, the general detection is to activate all the charging scan lines at the same time or by parity, and charge all the pixels or the pixels of the corresponding parity to make both the main pixel and the sub pixel at the same voltage level. However, the aforesaid ITO short cases cannot be effectively detected even with such detection, and then the yield descends and the production cost increases.